Generally it is not a good idea to leave connections open for someone that tries to gain access to your server. It opens doors to some very effective DOS attacks. Handling such cases by firewalling the requester for 15min is a much better solution. :twisted: If you agree, take a look at fail2ban.
I think it'd be really nice to be able to intercept these kinds of hack attempts and use ModRewrite to hand them off to a page that just never responds, the caller will be sat waiting for the page to timeout. That'll slow down anyone trying to use this kind of attack to trawl lots of servers for the ones that aren't properly secure. But Apache won't let you provide no response - it has to reply with something.